1. Field of the Invention
The present invention relates to a rotary electrical machine.
In particular, the invention relates to an alternator or an alternator-starter motor which is used for supplying the electrical circuit of a motor vehicle with energy.
The invention relates to a rotary electrical machine of the type comprising a rotor, a stator of generally cylindrical annular form which is arranged within a casing comprising a rear portion and a front portion, which are joined together along a junction plane at right angles to the axis of the rotor of the machine, of the type in which the external axial face of the stator delimits, with the internal axial face of the casing, an annular radial space, and of the type in which the stator is clamped axially between the opposed radial engagement surfaces which are formed in each of the two portions of the casing, with at least one elastically deformable element being interposed and compressed axially between each of the two engagement surfaces and a portion of the facing annular radial end face of the stator.
2. Description of Related Art
A rotary electrical machine of this type is described in the document FR-A-2 727 807.
In that type of rotary electrical machine, the stator is not in direct contact with the casing, but it is insulated from it by elastomeric pads and by air. In consequence, the stator is isolated from the vibration point of view, but it does not evacuate enough of the heat which is produced when the machine is working, and the working temperature then rises above the values that can be tolerated by the components of the machine.
In addition, the pads and seals used in that machine to act as vibration dampers are of relatively complex forms, which increases the cost of manufacturing and assembling the machine.
In the case where the seal used is of the type having an L-shaped cross section, fitting it on the stator is less easy to do within the cycle time of a quantity production process.
The invention aims to propose an improvement in such a type of rotary electrical machine which does not have the above mentioned drawbacks.
With this in view, the invention proposes a rotary electrical machine of the type defined above, characterised in that at least part of the radial annular space contains elastically deformable thermally conductive resin which is interposed radially between the casing and the stator, whereby to effect radial mechanical decoupling between the stator and casing, and whereby to dissipate heat energy from the stator to the casing.
In accordance with further features of the invention:
only the front portion of the casing contains the thermally conductive resin;
an elastically deformable flat annular seal is interposed axially between the, annular front radial end face of the stator and the engagement surface formed in the front portion of the casing;
a set of elastically deformable pads are spaced apart circumferentially and compressed axially between the rear annular radial end face of the stator and a portion of the engagement surface defined in the rear portion of the casing;
each pad includes a positioning lug in the form of a dovetail which is received axially in a complementary seating formed in the rear portion of the casing.
Thanks to the invention, the elastically deformable flat annular seal and the set of elastically deformable pads are protected due to the presence of the thermally conductive resin.
In addition, the alternator is simplified because a flat annular seal replaces an L-shaped annular seal of the prior art. The pads are simplified.
The pads and the seal, in particular, provide axial vibration damping.
The resin provides radial vibration damping.
Thanks to the resin, heat is evacuated efficiently so that it is possible to increase the power output of the alternator.
Thus in one embodiment, the volume of the winding of the rotor is increased.
In one embodiment, the rectifier unit is so configured that it gives this power increase and evacuates heat well.
In one embodiment, the conductor elements of the stator are clad in a linking layer to improve heat evacuation.
The invention also provides an alternator, especially for a motor vehicle, having at least one of the foregoing features.